Pneumatic sorting systems are employed in a variety of applications, including automated optical inspection and sorting equipment. Such pneumatic sorting systems for automated optical inspection are described in U.S. Pat. No. 5,318,173 of Datari for a "Hole Sorting System and Method" that is assigned to the assignee of this application.
FIG. 1 shows a prior art automatic inspection and sorting system 10 that is capable of inspecting and sorting, for example, raw or processed fruits or vegetables, such as apples, pears, potato chips, wood chips, recycled plastics, and other similar articles.
In operation, conveyor belt 12 carries articles 14 in a direction 16 through an inspection area 18 of a video camera 20. Video camera 20 delivers to a video signal characteristic of articles 14. Video signal processor 22 is programmed to identify particular characteristics of articles 14 such as, for example, color, shape, size, or the presence of defects. Articles 14 that include defect 24 can now be separated from articles 14 that do not include a defect.
After articles 14 pass through inspection area 18, they are propelled along a trajectory 26 toward an acceptance conveyor belt 28 that turns acceptable articles to subsequent processing station (not shown). Whenever video signal processor 22 determines from the video signal that an article 14 includes a defect 24, an ejection activation signal is delivered to a suitable one of multiple air ejection modules 30. In response to the ejection activation signal, ejection module 30 generates a blast of air 32 that deflects defective article 24 from trajectory 26 in a trajectory 27 toward a reject chute 34. Typically, articles 24 are deflected into reject chute 34 where they are funneled toward a reject conveyor belt 36 for removal. Reject chute 34 is intended to reduce spillage of defective articles.
A problem with prior art system 10 is that as video detection and processing technology improves, belt speeds of a sorting system such as shown in FIG. 1 have increased substantially. The sophistication of such sorters has significantly improved the throughput capacity and thus the performance efficiency of these state-of-the-art sorting systems provide accurate sorting of a variety of products according to multiple parameters at very high speeds.
The resulting high velocity of these rapidly conveyed and pneumatically ejected articles is high, and the high speed impact of the fragile articles such as potato chips on chute, conveyor belt, and other receiving surfaces may compromise the integrity of the articles, and undermine their saleability. A damaged article may not fulfill the specifications and standards of purchasers. Some damage, such as bruising and tearing of fruits, vegetables and other edible articles, may accelerate spoilage, thereby decreasing the shelf life of such an item. Indeed, with the improved quality of food products and processing, shelf lives of food items have increased in recent years. To keep pace with such escalating food quality standards, the need to minimize damage to food products is commensurately increased.
Addressing such heightened quality requirements in view of breakage-provoking sorter velocity rates, prior art mechanisms attempt to alleviate damage to articles caused by impact with a receiving surface have been developed. Such attempts were based on increasing the distance between the ejected article and any acceptance chutes, belt, or containers. However, reliance on mere distance alone and the limited product slowdown imposed by the combined forces of gravity and friction have proved insufficient to soften the surface impact to an extent required to reduce damage of fragile articles to an acceptable level, particularly in state-of-the-art inspection and sorting systems. In addition, space constraints in many sorting and processing facilities have limited the available distance that can be placed between ejectors and acceptance chutes or belts. This has compounded the need for a system which can soften the impact of and thereby prevent or minimize damage to an article impinging on a proximal surface. Moreover, as such systems utilize higher velocity rates, mere distance may not provide the deceleration required to prevent damage to the sorted articles. Thus, unfortunately, no prior sorting system has provided a mechanism that, to an acceptable extent, minimizes damage caused to articles by impact with a receiving surface after they have been pneumatically sorted.